With development of an information industry, especially with emergence of a data center, an optical communications system for high-speed data transmission is an inevitable development trend.
In an optical communications network, to load channel data carried in an electrical signal onto an optical signal for transmission, a laser is usually used to generate a beam of light. The electrical signal is modulated on the beam of light by a modulator, and sent to a fiber for transmission. An electro-absorption modulator (EAM) is a simple, cheap, and widely-used modulator. As shown in FIG. 1, an apparatus for loading two electrical signals onto two optical signals by using two EAMs is used to increase a communications capacity of an optical communications system. This apparatus includes three structures: a laser, a passive waveguide, and an EAM. The laser is configured to generate a laser ray, and needs a laminar structure that can ensure a largest gain. The passive waveguide is configured to divide an optical signal generated by the laser into two optical signals, and needs a laminar structure that can ensure a smallest splitting loss. The EAM is configured to modulate an electrical signal to one of the optical signals, and needs a laminar structure that can ensure optimal modulation performance. The three structures need to be implemented by using three different laminar structures, and each laminar structure needs an epitaxial growth. Therefore, this apparatus needs to undergo at least three epitaxial growths in a manufacturing process, and production is highly complex.